%S.  DEPARTMENT  OF  AGRp^r^RE, 

DIVISION  OF  ENTOMOLOGY — BULLETIN  NO.  35.  ifefe  fa!^  ft?  '  ' 


L.  O.  HOWARD,  Entomolog! 


REPORT  ON  CODLING  MOTH  INVEST KJATIONS 
IN  THE  NORTHWEST  DURING  1901. 

BY 

I 

a.  13.  si  m  p  &  b 

Invest  ig<  dor. 


WASHINGTON: 

GOVERNMENT   PRINTING  OFFICE. 
1  «,M>1>. 


DIVISION  OF  ENTOMOLOGY. 


Entomologist:  L.  0.  Howard. 

Fifst  Assistant  Erdofholpgist:  C.  L.  Marlatt. 

Assistant  Entomologists:  Th.  Pergande,  F.  H.  (Chittenden,  Nathan  Ranks. 
Investigators:  E.  A.  Sehwarz,  D.  W.  Coquillett,  W.  I).  Hunter,  C.  J».  Simpson. 
Apicuttu rat  Investigator:  Frank  Benton. 

Assistants:  R.  S.  Clifton,  F.  C.  Pratt,  Aug.  Busck,  Otto  Heidemann,  A.  N.  Caudell, 

J.  Kotinsky. 
Artist:  Miss  L.  Sullivan. 


U.  S.  DEPARTMENT  OF  AGRICULTURE, 

DIVISION  OF  ENTOMOLOGY— BULLETIN  NO.  35,  NEW  SERIES. 

L.  O.  HOWARD,  Entomologist. 


REPORT  ON  CODLING-MOTH  INVESTIGATIONS 
IN  THE  NORTHWEST  DURING  1901. 

BY 

C.  B.  SIMPSON, 

Investigator. 


WASHINGTON: 

GOVERNMENT  PRINTING  OFFICE. 

1902. 


LETTER  OF  TRANSMITTAL. 


U.  S.  Department  of  Agriculture, 

Division  of  Entomology, 
Washington,  D.  C,  May  ID,  1002. 
Sir:  1  have  the  honor  to  transmit  herewith  the  manuscript  of  a 
report  on  the  codling-moth  investigation  in  the  Northwest  during 
1901,  conducted  by  Mr.  C.  B.  Simpson,  a  special  agent  of  this  Division, 
and  prepared  by  him  for  publication.  Fruit  growers  in  the  North- 
west, and  especially  in  the  States  of  Idaho,  Washington,  and  Oregon, 
have  complained  that  conditions  in  that  part  of  the  country  must  be 
very  different  from  those  which  hold  in  the  Eastern  apple-growing 
sections,  inasmuch  as  the  remedial  treatment  which  is  found  satisfac- 
tory in  the  East  does  not  give  equally  good  results  in  the  Northwest. 
Therefore,  under  a  special  appropriation  from  Congress,  some  work 
was  begun  by  this  office  in  the  late  summer  of  1900,  Mr.  Simpson 
being  appointed  to  carry  out  the  investigation  and  experiments.  A 
report  upon  the  work  which  he  did  in  the  season  of  1900  was  published 
in  Bulletin  30  (new  series)  of  this  Office  (pp.  51-63).  In  1901  he  was 
able  to  make  a  somewhat  earlier  start,  and  the  results  were  therefore 
more  satisfactory.  This  work  is  described  in  the  accompanying  bul- 
letin. The  present  summer  (1902)  Mr.  Simpson  started  for  the  field 
early  in  May,  and  it  is  hoped  that  at  the  close  of.  the  season  the  investi- 
gation will  have  arrived  at  such  a  point  as  to  enable  the  publication  of 
a  full  and  satisfactory  bulletin  covering  the  whole  problem.  1  recorm 
mend  this  bulletin  to  be  published  as  No.  35  (new  series). 
Respectfull}7, 

L.  O.  Howard, 

Hon.  James  Wilson,  Entomologist. 
Secretary  of  Agriculture. 

2 


CONTENTS. 


Pai?e. 

Itinerary   5 

Work  done  from  Ithaca,  N.  Y  :   6 

Teachers'  institutes   6 

Status  of  the  fruit  crop  for  1901   6 

Injury  due  to' codling  moth  in  1901   7 

Fruits  infested  by  the  codling  moth   7 

Introduction  and  spread  of  the  codling  moth  in  the  Northwest     8 

Life  zones  and  present  distribution   9 

Life  history  of  the  codling  moth   10 

The  egg   10 

The  larva   10 

The  pupa   13 

The  moth   13 

Generations  of  the  insect   15 

Overlapping  of  generations   18 

Causes  and  conditions  which  affect  the  numbers  of  this  insect   18 

Preventive  measures  employed  against  the  codling  moth   19 

Remedial  measures  employed  against  the  codling  moth   20 

Measures  against  the  larvre   20 

Spraying   21 

Early  sprayings   21 

Later  sprayings   22 

Material  for  the  spray   24 

Expense  of  spraying   25 

Picking  and  destroying  wormy  fruits   25 

Banding   26 

Measures  against  the  adult  '   27 

Trap  lanterns   27 

Baiting  the  moth   27 

Resume  and  conclusion   27 

3 


ILLUSTRATIONS. 


PLATES. 

Page. 


Plate  I.  Entrance  holes  of  larvfe   12 

II.  Fig.  1. — Banded  tree  and  near-by  fence.    Fig.  2. — Post  of  fence  shown 

above,  with  splinters  removed   12 

III.  Fig.  1. — Portion  of  fence  post,  showing  old  pupa  skins.  Fig. 

2. — Cocoons  in  cracks  in  bark   ]2 

IV.  Fig.  1. — Piece  of  bark,  showing  moth  just  emerged,  and  old  pupa 

skins.    Fig.  2. — Band  on  which  the  remains  of  330  cocoons  were 

counted   16 

V.  Views  in  orchard  of  Hon.  Edgar  Wilson,  showing  location  of  apple 

house  in  relation  to  orchard   20 


TEXT  FIGURE. 


Fig.  1.  Map  of  Pacific  Northwest,  showing  life  zones 
4 


9 


REPORT  ON  CODLING-MOTH  INVESTIGATIONS  IN  THE 
NORTHWEST  DURING  1901. 


ITINERARY. 

In  accordance  with  the  authorization  of  the  Secretary  of  Agricul- 
ture and  the  instructions  of  the  Entomologist,  the  following  report  is 
submitted  upon  the  investigations  of  the  codling  moth  in  the  Pacific 
Northwest  for  1901. 

I  left  Ithaca,  N.  Y.,  June  15,  for  Idaho,  arriving  at  Salt  Lake  City, 
Utah,  June  19.  The  Utah  Agricultural  College  was  visited  and  con- 
ferences were  held  with  the  authorities  in  regard  to  the  codling  moth. 
From  Logan  I  went  to  Pocatello,  Idaho,  and  thence  to  Market  Lake, 
Idaho,  to  look  over  a  grasshopper  outbreak.  At  that  place  I  found 
Professor  Aldrich  and  with  him  looked  over  the  infested  .section. 
A  report  of  the  results  of  this  work  has  already  been  submitted. 
June  24  I  left  Market  Lake  and  was  accompanied  by  Prof essor  Aldrich 
to  Shoshone,  Idaho,  from  which  place  I  went  to  Shoshone  Falls  and 
Blue  Lakes.  Mr.  Perrine's  orchard  at  Blue  Lakes  was  examined 
closely  and  remedial  measures  were  advised.  The  28th  and  29th  I 
spent  in  observing  conditions  about  Mountainhome,  arriving  at  Boise 
the  29th,  where  I  spent  a  few  days  in  looking  over  the  orchards  in 
that  vicinity.  A  trip  was  then  made  to  Narnpa,  Caldwell,  Payette,  and 
Weiser,  Idaho,  with  return  to  Boise  the  13th  of  July.  Many  trips 
were  made  to  orchards  about  Boise.  August  14  another  trip  was 
made,  which  included  Nampa,  Caldwell,  Payette,  Weiser  and  Emmett. 
Returning  to  Boise  August  25,  I  remained  there  two  days  and  then 
was  in  Mountainhome  from  the  27th  to  the  30th.  In  September  sev- 
eral trips  were  made  to  Beatty,  Nampa,  and  Meridian,  and  one  to 
Payette. 

October  4  I  went  to  Portland,  Oreg.,  for  the  purpose  of  attending 
the  fruit  fair  and  conferring  with  the  Oregon  people.  I  had  a  long 
talk  with  Professor  Cordley  and  others  of  the  Oregon  Agricultural  Col- 
lege and  from  there  went  to  southern  Oregon.  From  southern  Oregon 
I  returned  to  Portland  and  from  there  went  to  Moscow,  Idaho.  In  com- 
pany with  the  Entomologist  and  Professor  Aldrich,  I  left  Moscow 
October  18.  After  spending  several  days  at  Boise,  I  started  for  Wash- 
ington, D.  C,  October  22  and  arrived  there  on  the  26th. 

5 


6 


WORK  DONE  FROM  ITHACA,  N.  Y. 

Not  being  able  to  begin  work  in  the  field  early  enough  to  make 
observations  during  the  blossoming  period,  circular  letters  were  sent 
to  prominent  growers  in  Idaho  asking  them  to  conduct  observations 
and  begin  experiments. 

Letter  No.  1  asked  for  observations  in  regard  to  the  times  of  bloom- 
ing, etc.,  and  on  life  of  the  insect  during  that  period.  Several  ren- 
dered valuable  aid  by  making  excellent  observations. 

Letter  No.  2  asked  several  growers  to  begin  cooperative  experiments, 
which  the  writer  would  complete  when  he  arrived  upon  the  field.  In 
every  case  the  freeze  of  J une  5  left  no  apples  upon  the  trees  which 
were  selected  for  the  experiments.  Much  work  had  been  done  by 
some  growers  in  starting  these  tests. 

Letter  No.  3  was  sent  to  60  growers  in  different  parts  of  the  State 
asking  that  band  records  be  kept.  The  fruit  growers  responded  well 
to  this  request,  and  over  40  replies  were  received.  Many  valuable 
records  were  obtained. 

TEACHERS'  INSTITUTES. 

During  the  summer  the  writer  addressed  four  teachers'  institutes 
upon  the  subject  of  the  codling  moth,  the  aggregate  number  of  teachers 
present  being  about  180. 

In  each  of  these  talks  the  damage  caused  by  the  insect  and  the  impor- 
tance of  the  subject  were  dwelt  upon.  A  brief  but  fundamental 
sketch  of  the  life  history  was  given,  fully  illustrated  by  photographs 
and  specimens  of  the  insect's  work.  The  most  approved  methods  of 
control  were  explained  and  the  results  obtained  by  the  same  were 
given.  The  teachers  were  told  how  they  might  introduce  the  subject 
into  their  school  work  as  a  nature-study  topic.  Directions  were  given 
as  to  the  method  of  presenting  the  work  and  collection  of  specimens. 
In  these  talks  the  writer  took  great  pains  to  interest  the  teachers  and 
has  been  rewarded  by  knowing  that,  in  a  great  number  of  instances, 
the  teachers  put  the  suggestions  into  practice. 

On  account  of  the  small  fruit  crop  no  summer  meeting  of  the  State  hor- 
ticultural society-  was  held.  Two  farmers'  meetings  were  addressed — 
one  at  Caldwell  and  another  at  Mountainhome.  The  attendance  was 
poor,  but  the  interest  shown  amply  repaid  the  efforts  exerted. 

STATUS  OF  THE  FRUIT  CROP  FOR  1901. 

Early  in  the  spring  the  fruit  crop  of  1901  promised  to  be  large.  A 
sudden  freeze  June  5,  at  which  time  apples  were  about  the  size  of 
marbles,  practically  ruined  all  prospect  for  a  good  crop.  About  Boise 
prunes  and  peaches  were  all  killed,  and  in  some  orchards  no  apples 
were  left,  while  in  others  considerably  over  half  a  crop  remained.  In 
other  sections  conditions  were  about  the  same.    Mr.  McPherson  esti- 


7 


mates  that  there  was  only  about  10  per  cent  of  an  apple  crop  in  Idaho 
in  1901,  and  his  estimate  is  probably  not  far  from  correct. 

On  account  of  this  short  crop  the  price  of  apples  was  high  and  those 
who  could  save  a  large  part  of  what  crop  they  had  made  good  profits. 

INJURY  DUE  TO  CODLING  MOTH  IN  1901. 

On  account  of  the  small  crop  it  is  impossible  to  give  an  estimate  that 
is  of  any  value  in  regard  to  the  damage  by  the  insect  in  1901.  It  was 
certainly  much  greater  than  in  1900. 

In  orchards  with  but  little  fruit  the  apples  were  all  wormy,  man}' 
of  them  containing  from  5  to  10  holes.  The  writer  counted  the 
remains  of  23  eggs  on  one  apple  and  17  on  another. 

The  number  of  the  insects  was  decreased  but  little  by  the  freeze, 
while  the  number  of  fruits  they  had  to  work  upon  was  greatly  les- 
sened. Consequently,  in  the  orchards  that  were  well  cared  for  a  large 
percentage  of  the  fruits  was  wormy  in  spite  of  spraying  and  banding. 
The  following  are  estimates  of  injury  by  the  codling  moth  in  individ- 
ual orchards  and  in  localities: 

M.  A.  Kurtz,  at  Xampa,  had  over  half  a  crop  of  apples.  Many  of  them  were  under- 
sized. SprayiDg  and  banding  were  well  done.  The  loss  for  the  whole  orchard  was 
about  20  per  cent. 

Mr.  C.  Hinze,  Payette,  had  about  half  a  crop  of  Jonathans.  About  50  per  cent 
was  saved  from  this  insect.    Spraying  alone  was  used. 

Hon.  Edgar  "Wilson  had  a  small  crop  of  Ben  Davis  and  Jonathans.  Early  spray- 
ings were  made  and  bands  were  used.    Less  than  40  per  cent  of  these  were  saved. 

Mr.  John  McGlinchey  had  nearly  a  full  crop  at  Payette.  Early  sprays  were  made 
but  banding  was  neglected.    Not  over  20  per  cent  was  saved. 

Mr.  Seth  Heath,  9  miles  from  Mountainhome,  thinks  he  saved  80  per  cent  of  his 
apples  and  pears.    Spraying  and  banding  and  other  measures  were  used. 

Mr.  W.  S.  Whitehead,  of  Boise,  saved  only  about  20  per  cent  by  spraying  and  no 
banding. 

Many  orchards  were  noted  in  various  localities  where  all  the  fruit  was  wormy. 
Professor  Aldrich  has  found  that  the  damage  in  and  about  Moscow  was  about  5 
per  cent. 

It  was  reported  that  about  Walla  Walla,  Wash.,  and  in  the  valley  of  the  upper 
Columbia  River  the  conditions  were  about  as  they  were  in  the  Boise  Valley. 

In  the  Willamette  Valley  the  writer  has  been  told  that  the  injuries  where  no  meas- 
ures were  used  varied  from  30  to  80  per  cent. 

In  southern  Oregon  the  writer  found  orchards  near  Central  Point  in  which  the 
injury  did  not  exceed  5  per  cent.  In  an  untreated  orchard  20  per  cent  of  the  apples 
were  estimated  to  be  damaged.  Growers  said  that  this  orchard  showed  much  less 
injury  than  many  others  in  that  locality. 

FRUITS  INFESTED  BY  THE  CODLING  MOTH. 

The  apple  is  by  far  the  most  subject  to  the  attack-  of  this  pest,  and 
practically  all  of  the  work  has  been  directed  against  the  insect  in  this 
fruit. 

In  1900  it  was  noted  that  some  varieties  of  apples  were  more  subject 


s 


to  the  attacks  of  this  moth  than  others,  and  a  list  was  prepared  in  order 
of  injury.    In  1901  but  little  revision  of  the  list  was  necessaiy. 
The  following  is  the  revised  list: 

Pewaukee  (always  badly  infested). 
Red  Astrakan. 
Bell  flower  varieties. 
Spitzenberg. 

Grimes  Golden,  Northern  Spy,  Grravenstein. 

Wealthy. 

Baldwin. 

Ben  Davis  ( very  variable) . 
Rome  Beauty  (variable). 
Jonathan. 

Winesap  (always  least  infested). 

This  list  was  made  from  observations  in  many  orchards  and  is  a 
composite  of  the  conditions  in  these  orchards.  Local  conditions  are 
to  a  great  extent  the  cause  of  the  variability. 

Pears  are  but  little  infested  when  compared  with  apples.  In  the 
very  worst  localities  the  injury  sustained  rarely  if  ever  reaches  20 
per  cent,  and,  when  remedial  measures  are  used,  injury  varies  from  5 
to  15  per  cent. 

Man}7  quinces  were  examined,  but  not  a  single  case  of  infestation 
was  noted. 

Having  in  mind  Professor  Bruner's  observations  wdien  he  found 
larva?  which  lie  took  to  be  those  of  the  codling  moth  feeding  in  seed  - 
pods  of  roses,  the  writer  examined  hundreds  of  these  pods  without 
finding  any  larvae  or  eggs. 

It  has  often  been  reported  that  the  codling  moth  larvae  wore  attack- 
ing peaches,  prunes,  and  plums.  Upon  investigation  it  was  found  in 
ever}7  case  that  the  attack  was  made  by  the  larva  of  the  peach-twig 
borer. 

INTRODUCTION  AND  SPREAD  OF  THE  CODLING  MOTH  IN  THE 

NORTHWEST. 

Dr.  C.  V.  Riley,  in  his  Sixth  Missouri  Report  (1874),  mentions  this 
insect  as  working  in  Utah,  where  it  had  evidently  been  introduced  a 
year  or  two  previous. 

The  Scientific  American  of  November  II,  1882,  mentions  that  the 
codling  moth  made  its  appearance  in  California  in  1874. 

Prof.  J.  M.  Aldrich  states  that  this  insect  has  been  known  in  the 
Clearwater  Valley  since  1887,  and  in  southern  Idaho  nearly  as  long. 
By  many  orchardists  in  southern  Idaho  the  writer  was  told  that  the 
above  date  is  approximate^  correct.  Many  stories  are  told  of  how 
the  insect  reached  Idaho,  one  being  to  the  effect  that  the  insect  was 
introduced  in  dried  prunes.  Without  doubt  the  insect  was  introduced 
in  apples  shipped  either  from  Utah,  Oregon,  or  Washington.  When 


9 


once  introduced  it  can  be  readily  understood  how  the  insect  spread 
over  the  apple-growing  area  by  the  shipping  of  fruit  from  one  section 
to  another.  The  spread  is  found  to  be  along  the  lines  of  transporta- 
tion. It  was  retarded  in  a  great  measure  by  the  fact  that  many 
orchards  were  isolated.  A  well-marked  case  of  immunity  resulting 
from  isolation  is  shown  in  the  case  of  Mr.  Perrine's  orchard  at  Blue 
Lakes.  This  orchard  was  free  from  the  insect  until  two  or  three  years 
ago.  and  is  now  but  little  infested.  Mr.  Perrine  thinks  the  moth  was 
introduced  into  his  orchard  in  old  boxes.  The  spread  from  orchard  to 
orchard  by  the  flight  of  the  moths  has  been  comparatively  slow,  and 
usually  follows  a  river  valley. 

LIFE  ZONES  AND  PRESENT  DISTRIBUTION. 

The  status  of  the  insect  has  been  studied  as  far  as  the  data  at  hand 
would  permit.  The  life  zones  found  in  Idaho  (fig.  1.)  may  be  de- 
scribed as  follows:  . 

The  Boreal  zone  comprises  that  part  of  the  State  known  as  the  Panhandle,  a  strip 
along  the  northeastern  side  of  the  State  and  a  large  area  in  the  central  part  of  the 
State  which  is  connected  with  the  eastern  strip. 


Fig.  1.— Map  of  the  Pacific  Northwest,  showing  life  zones— locaities  infested  by  codling 

cated  by  dots. 


The  Transition  zone  is  limited  to  an  irregular  area  in  the  north  and  a  fringe  around 
the  Boreal  in  the  south.  The  southwestern  and  southeastern  parts  of  the  State  are 
also  in  this  zone.  The  Transition  area  in  the  northern  part  of  the  State  is  somewhat 
different  from  that  of  the  southern  part,  on  account  of  the  larger  amount  of  rainfall. 


10 


The  Upper  Ronoran  comprises  the  area  about  the  Snake  River  Valley.  This  area 
is  continuous  with  the  same  zone  in  Oregon  on  the  west  and  Utah  on  the  south.  An 
arm  extends  down  the  Snake  River  Valley  on  the  western  border.  A  small  area  of 
this  zone  is  present  in  the  valleys  of  the  Snake  and  Clearwater  rivers  at  Lewiston. 
At  this  point  several  of  the  Lower  Sonoran  fruits  are  grown. 

The  relations  of  the  codling  moth  to  these  zones  are  as  follows: 

Boreal. — As  no  apples  can  be  grown  in  this  zone,  this  insect  does  not  occur. 

Transition.  -The  insect  occurs  in  this  zone,  but  is  never  greatly  injurious.  At  Mos- 
cow the  injuries  for  the  past  three  years  have  been  21, 10,  and  5  percent,  respectively. 
Many  fruit  growers  have  told  the  writer  that  the  insect  has  its  ups  and  downs,  vary- 
ing from  practically  no  injury  to  25  per  cent.  Correspondents  at  Almo,  Cassia 
County;  Lakeview,  Laclede,  and  Rathdrum,  Kootenai  County ;  and  Paris,  Bear  Lake 
County,  state  that  they  can  find  no  indications  of  the  insect  at  those  places.  The 
observations  of  those  in  the  best  position  to  know  indicate  that  these  locations  are 
not  well  fitted  for  the  growing  of  apples.  The  northern  part  of  this  zone,  however, 
is  evidently  more  suitable  for  apples  than  the  southern  part. 

The  Upper  Sonoran. — From  80  to  90  per  cent  of  the  fruit  raised  in  Idaho  is  grown  in 
this  zone.  Some  varieties  of  apples  reach  perfection.  The  codling  moth  reaches  its 
maximum  of  numbers  and  destructi veness  in  this  zone,  and  here  the  greater  part  of 
the  investigation  has  been  made. 

LIFE  HISTORY  OF  THE  CODLING  MOTH. 

Many  important  variations  in  the  life  history  of  this  insect  were 
noted  in  1901. 

THE  EGG. 

As  in  1900.  many  eggs  were  observed.  Jn  orchards  where  there 
were  but  few  apples  eggs  were  found  in  enormous  numbers.  On  one 
apple  the  number  of  eggs  or  remains  of  eggs  was  found  to  be  23 
(PI.  I.  />);  on  another  17.  It  was  difficult  to  ascertain  the  time  of 
hatching  of  the  eggs,  but  the  times  of  hatching  of  eight  were  found 
with  reasonable  accuracy.  These  hatched  in  from  three  to  eight  days, 
with  an  average  of  about  five  days. 

THE  LARVA. 

In  a  day  or  so  after  the  egg  is  laid,  a  horseshoe-shaped  band,  which 
is  the  embryonic  larva,  may  be  seen.  Later  the  form  of  the  larva 
may  be  easily  distinguished.  In  about  live  days  the  fully  formed 
larva  breaks  its  way  through  the  shell  and  immediately  seeks  to  enter 
an  apple.  The  writer  has  many  times  attempted  to  observe  the  hatch- 
ing of  an  egg  and  the  entering  of  the  apple,  but  has  failed,  although  a 
few  times  the  attempt  was  almost  successful.  The  young  larva  of  the 
first  generation  has  been  observed  to  spend  some  time  upon  the  fruit 
and  then  to  enter  the  calyx  by  squeezing  its  way  in  between  the  calyx 
lobes. 

In  1900  the  earlier  countings  showed  that  about  GO  per  cent  entered 
the  calyx  end.    Without  doubt  this  low  percentage  was  caused  by 


11 


including  the  early  individuals  of  the  second  generation.  In  1901,  by 
numerous  countings,  the  average  was  found  to  be  83  per  cent,  with  a 
minimum  of  79  per  cent.  In  one  counting  of  130  apples,  106  had 
entered  the  calyx  and  21  the  side.  About  half  of  those  that 
entered  by  the  side  entered  where  the  apples  touched.  In  12  apples 
there  were  two  worms  each.  Three  larva4  were  killed  by  fungi  or 
bacteria.  Of  those  which  had  left  the  apples,  13  had  left  by  the  calyx 
and  IT  by  the  side. 

By  far  the  larger  number  of  the  larva?  of  the  later  generation  enter 
the  apple  at  other  places  than  the  calyx — in  some  cases,  from  90  to  100 
per  cent.  They  enter  at  the  sides  (PI.  I),  at  the  stem,  and  particu- 
larly where  the  apples  touch.  In  badly  infested  orchards  it  is  a  rare 
exception  to  find  apples  which  touch  without  rinding  also  the  entrance 
place  of  a  codling-moth  larva. 

A  few  larvae  of  the  second  generation  were  taken  out  of  their  bur- 
rows a  few  hours  after  they  had  entered  and  were  placed  upon  apples  in 
order  to  see  what  they  would  do.  All  immediately  commenced  search- 
ing for  a  place  to  enter.  The}T  would  try  to  bite  through  the  smooth 
skin,  but  their  jaws  would  make  but  little  impression.  One  of  them 
entered  at  the  stem,  another  found  a  broken  place  in  the  skin,  and 
another  succeeded  in  piercing  the  smooth  skin.  As  has  been  noted  by 
other  observers,  1  found  that  the  larvae  while  entering  eat  but  little,  if 
any,  of  the  skin  or  flesh  of  the  fruit,  but  push  the  particles  out  behind 
them.  They  seem  intent  upon  getting  away  from  the  light.  Professor 
Cordle}T  states  that  he  has  seen  them  spin  silk  over  the  mouths  of  the 
holes  as  soon  as  they  have  fully  entered. 

A  few  authors  have  advanced  the  opinion  that  those  larva1  which 
hatch  on  the  leaves  eat  sparingly  of  the  leaves  before  they  rind  the 
apples.  In  spite  of  many  attempts  to  throw  light  upon  this  point,  the 
writer  can  offer  no  evidence;  but  he  believes  that  many  perish  on 
account  of  this  habit,  as  they  get  any  poison  that  may  be  on  the  leaves. 
In  the  field  a  large  majority  of  newly  hatched  larvae  never  reach  an 
apple,  but  perish.  This  was  especially  true  in  1901  on  account  of  the 
scarcity  of  apples.  The  apples  which  had  23  and  IT  eggs  had  only  5 
and  1  worm  holes,  respectively. 

When  entering  by  way  of  the  calyx,  the  larva  eats  its  first  few  meals 
at  the  surface  before  commencing  its  burrow  into  the  fruit.  On  enter- 
ing at  the  side,  the  larva  eats  out  a  circular  mine  immediately  under 
the  skin,  which  can  be  easily  distinguished  by  its  lighter  color.  In 
about  three  to  five  days  the  larva,  after  making  its  burrow  funnel- 
shaped,  starts  toward  the  central  portion  of  the  fruit.  When  the  calyx 
is  entered  a  large  amount  of  castings  is  thrown  out  (PI.  I,  D),  hut 
when  the  side  is  entered  but  a  small  amount  is  thrown  out  (PI.  1, 
A,  B,  C).  When  the  central  portion  of  the  fruit  is  reached  the  larva 
eats  out  an  irregular  cavity  which  is  found  rilled  with  pellets  of  excre- 


12 


ment  bound  together  with  silk.  Data  as  to  how  long  it  takes  the  larva 
to  become  full  grown  were  secured.  However,  the  number  of  experi- 
ments and  the  number  of  larvae  wi  re  small  and  more  work  must  be 
done  before  a  good  average  can  be  given.  The  shortest  time  Avas 
fourteen  days  and  the  longest  twenty-five,  with  twenty-one  days  as  an 
average.  When  the  larva  is  full  grown  it  eats  its  way  to  the  outside 
of  the  apple,  but  remains  within,  plugging  the  hole  with  frass.  In 
a  day  or  so  this  obstruction  is  pushed  out,  and  the  larva  crawls  out 
and  immediately  seeks  a  place  in  which  to  spin  its  cocoon  and  complete 
its  transformation. 

The  effect  of  this  insect  on  the  apples  and  pears  is  such  that  they 
ripen  prematurely  and  fall  from  the  tree,  being  worthless  for  com- 
mercial purposes. 

The  larva  makes  its  way  from  the  apple  to  the  place  of  spinning  its 
cocoon  in  one  of  three  ways.  Most  commonly  it  simply  crawls  from 
the  apple  to  a  twig,  thence  to  branch,  and  thence  to  the  trunk  of  a 
tree.  Experiments  conducted  by  Professor  Aldrich  upon  trees  with  5 
bands  show  that  twice  as  many  larvae  spin  their  cocoons  under  the  top 
band  as  under  any  intermediate  band,  and  the  next  highest  number 
was  found  under  the  bottom  band.  In  case  of  windfalls,  the  larvae 
leave  the  apple  and  crawl  to  a  suitable  place  along  the  ground.  In  a 
few  cases  the  larvae  drop  from  the  tree  to  the  ground  by  a  silken 
thread.    Many  of  these  threads  have  been  noted  b}^  the  writer. 

The  larvae  spin  their  cocoons  in  a  variety  of  places.  Those  noted  are 
as  follows:  Under  loose  pieces  of  bark  (PI.  Ill,  fig.  2)  on  rough  trees; 
in  the  cracks  in  the'  crotches  of  trees;  in  cracks  or  holes  in  the  tree 
trunks;  under  splinters  on  fence  posts  (PI.  II,  and  tig.  1  of  PI.  Ill); 
in  the  rough  bark  of  adjacent  trees  (PI.  Ill,  fig.  2);  in  any  kind  of 
rubbish  about  the  trees;  under  anything  lying  against  or  upon  the 
trees;  in  cracks  in  the  dr}^  earth  about  the  trees;  and,  in  some  few 
cases,  in  dried  fallen  apples.  The  place  of  first  choice  under  normal 
conditions  is  under  the  loose  bark,  in  the  crotches,  or  in  the  holes  or 
cracks  in  the  tree.  When  the  tree  is  smooth  and  the  earth  is  dry  we 
sometimes  find  a  considerable  number  of  cocoons  in  the  cracks  in  the 
earth. 

In  general  the  larva  selects  a  dry,  tight  place,  and  it  may  gnaw  out 
a  hole  in  the  bark  and  incorporate  the  pieces  in  the  cocoon.  Many 
times  a  silk  tube  2  or  3  inches  in  length  is  found  with  a  cocoon  at  one 
end.  Evidently  the  larva  did  not  find  a  place  tight  enough  and  con 
tinued  spinning  until  such  a  place  was  made.  In  these  cases  a  cap  of 
silk  is  found.  Cloth  bands  furnish  a  place  for  spinning  cocoons  most 
acceptable  to  the  larvae. 

The  larva  spins  its  cocoon  in  about  two  days.  The  cocoon  is  com 
posed  of  a  single  thread  of  silk,  a  product  of  the  silk  glands  common 


Bui.  35,  New  Series,  Div.  of  Entomology,  U.  S.  Dept.  of  Agriculture. 


Plate  I. 


Entrance  Holes  of  Larv/e. 


Bui.  35,  New  Series,  Div.  of  Entomology,  U.  S.  Dept.  of  Agriculture. 


Plate  II. 


Fig.  2.— Post  of  Fence  shown  above,  with  Splinters  removed. 


13 


to  the  larva?  of  this  order  of  insects.  The  cocoons  of  the  early  gener- 
ation are  fragile  and  not  so  heavy  or  well  made  as  those  of  the  later 
generation,  in  which  the  larva  passes  the  winter. 

THE  PUPA. 

The  larva  when  spinning  its  cocoon  is  bent  upon  itself,  but  when 
the  spinning  is  completed  it  straightens  and  becomes  shorter  and 
thicker.  In  about  live  days  it  sheds  its  last  larval  skin  and  becomes  a 
pupa.  One  can  always  find  this  skin  in  a  pellet  at  the  caudal  end  of 
the  pupa.  The  pupa  is  about  half  an  inch  long  and  at  first  is  a  pale 
yellow  color,  later  becoming  brown.  The  last  day  before  the  moth 
emerges  it  assumes  a  bronze  color.  The  antenna?,  mouth-parts,  legs, 
and  wings  of  the  moth  may  be  clearly  seen,  all  soldered  together  in  an 
immovable  mass.  The  segments  of  the  abdomen  are  movable  and  are 
armed  on  their  caudal  edge  with  spines  which  point  backward. 

Some  time  after  the  beginning  of  warm  weather  in  the  spring,  or 
twenty-one  or  twenty-two  days  after  commencing  the  spinning  of  the 
cocoon,  in  the  summer,  the  moth  emerges.  The  pupa  pushes  itself 
through  the  wall  of  the  cocoon  and  out  free  from  any  obstruction. 
This  is  accomplished  by  rapid  movement  of  the  abdomen,  aided  by 
the  spines  which  point  backward.  Pupa?  were  observed  to  have 
moved  themselves  fully  an  inch  before  a  suitable  place  for  emergence 
was  found.  They  sometimes  thrust  themselves  through  muslin  or 
burlap  when  such  is  used  for  bands  and  neglected.  Soon  after  the 
pupa  is  free  from  the  cocoon  the  pupa  skin  splits  down  the  back  and 
the  moth  slowly  crawls  out.  Man}'  experiments  were  carried  out  to 
determine  the  time  elapsing  between  the  spinning  of  the  cocoon  and 
the  emergence  of  the  moth.  The  shortest  time  was  twelve  days,  and 
the  longest  during  the  summer  was  twenty-eight  d&ys,  with  an 
average  of  twenty-two.  Only  a  very  small  percentage  emerge  the 
twelfth  day. 

THE  MOTH. 

Upon  emerging  the  wings  of  the  moth  are  small,  the  legs  weak,  and 
the  body  soft.  The  moth  clings  to  the  bark  head  up  (PI.  IV,  fig.  1), 
the  wings  gradually  expand,  and  the  legs  and  body  harden  and  get 
stronger.  Later  the  moth  holds  its  wings  for  a  few  minutes  above  its 
back,  like  a  butterfly.  The  wings  are  then  replaced  and  the  moth  is 
ready  for  flight.  During  all  these  proceedings  the  moth  carefully 
avoids  the  sunlight.  After  the  wings  are  fully  expanded  and  dry  the 
moth  frequently  changes  its  position  by  running  rapidly  up  the  tree. 
In  from  ten  to  thirty  minutes  after  emerging  the  moth  usually  flies  to 
the  lower  branches  of  the  tree  and  is  lost  as  far  as  further  observation 
is  concerned.  Quick,  somewhat  erratic  flight  is  characteristic,  the 
flight  being  so  rapid  that  the  eye  can  not  follow  it. 


14 


It  is  generally  stated  by  writers  on  this  insect  that  the  adult  is  but 
rarely  seen  in  orchards.  During  the  summer  of  1900  the  writer  saw 
only  about  half  a  dozen  moths  in  the  Held.  During  the  summer  of  1901 
from  one  to  three  were  seen  every  day  spent  in  orchards.  These  were 
usually  on  the  fruit  or  on  the  upper  surfaces  of  the  leaves.  On  being 
disturbed  they  would  Hit  away  and  be  lost  to  sight. 

But  few  fruit  growers  are  familiar  with  the  adult  form  of  this 
insect.  On  this  account  many  mistakes  are  made  as  to  its  identity. 
Anyone  can  easily  confine  larvae  or  pupa1  and  in  a  short  time  settle  the 
question  of  identity.  The  moth  is  quite  variable  in  size,  but  never 
expands  more  than  an  inch.  The  wings  at  a  glance  have  the  appear- 
ance of  watered  silk,  but  upon  closer  examination  one  finds  them 
crossed  by  numerous  rows  of  gray  and  brown  scales,  which  give  the 
appearance  of  the  plumage  of  a  bird.  Behind  the  tip  of  the  forewing 
there  is  a  large  dark-brown  spot  which  hears  rows  of  bronze  and  gold- 
colored  scales.  The  hind  wings  are  of  a  light  grayish  color,  darker 
toward  the  margin. 

The  sexes  may  be  readily  distinguished  by  the  fact  that  the  males 
bear  a  black  pencil  of  hairs  on  the  upper  surface  of  the  hind  wing 
and  a  black  spot  on  the  under  surface  of  the  forewing. 

Mr.  Hitt,  of  Weiser,  found  in  1896  that  of  50  moths  but  7  were 
males.  The  writer  found  the  females  exceeding  the  males  in  number, 
but  can  give  no  figures. 

During  the  summer  of  1900  the  writer  found  a  moth  on  the  trunk 
of  a  tree  that  had  all  the  appearance  of  a  codling  moth  except  the 
color,  which  was  buff  and  gold  throughout,  the  bronze  spot  being 
much  the  same  as  in  the  codling  moth.  During  the  summer  of  1901, 
1  well  preserved  and  8  badly  worn  specimens  having  the  same  color 
were  secured,  and  2  others  were  observed  in  the  field.  Mr.  Hitt,  of 
Weiser.  found  7  of  these  moths  among  50  moths  bred  in  1896.  Mr. 
McPherson  has  also  noted  this  bufi'-colored  moth.  Whether  this  is  a 
variety  of  Cori><><  <q>saj)omonella  or  another  species  has  not  yet  been 
determined. 

According  to  many  observers  the  codling  moth  has  been  seen  to  feed 
upon  the  juice  of  ripe  apples.  Many  fruit  growers  tell  me  that  they 
have  seen  many  moths  about  cider  mills  and  have  seen  them  feed  on 
cider. 

The  conclusion  arrived  at  by  all  investigators  of  this  insect  is  that 
it  is  but  little  attracted  to  lights  such  as  are  used  in  trap  lanterns. 
The  writer  finds,  however,  that  moths  will  seek  a  window  when  they 
have  emerged  in  a  dark  room  or  cellar. 

In  cages  the  egg  laying  begins  the  second  day  after  emergence  and 
has  been  observed  to  continue  until  the  fourth  day.  In  the  field  some 
eggs  were  observed  to  have  been  laid  in  the  late  afternoon  and  early 
evening. 


15 


The  moths  lay  practically  all  of  the  egg*  of  the  first  generation 
upon  the  fruit.  Avhile  those  of  the  later  generation  are  laid  both  upon 
the  fruit  and  leaves.  From  many  observations  the  writer  is  led  to 
believe  that  there  is  no  general  rule  as  regards  the  eggs  of  the  second 
generation.  In  some  orchards  the  majority  were  found  upon  the  fruit, 
and  in  others  upon  the  leaves. 

In  eages  the  moths  rarely  live  over  a  week. 

( i  FENERATIONS  OF  THE  INSECT. 

From  the  economic  standpoint  the  number  of  generations  is  an 
important  feature,  as  that  is  the  chief  factor  in  determining  the  amount 
of  damage.  In  the  Eastern  States  the  generations  vary  from  one  and 
a  partial  second  to  two  and  a  partial  third.  In  California,  Oregon, 
New  Mexico,  and  Alabama,  various  investigators  have  published  the 
statement  that  three  generations  occur.  Professor  Gillette  has  recently 
come  to  the  conclusion  that  there  are  only  two  generations  in  Colorado. 
Professor  Cordley  says  that  there  are  only  two  at  Corvallis,  Oreg. 
In  south  Idaho,  both  Mr.  McPherson  and  Mr.  Hitt  have  advanced  the 
idea  that  there  are  three  full  generations,  and  sometimes  a  partial 
fourth. 

The  writer  has  regarded  this  as  one  of  the  most  essential  points  to 
be  determined  in  the  investigation  of  this  insect.  In  1900  an  attempt 
was  made  to  solve  the  problem.  At  the  end  of  the  season,  though  but 
little  data  had  been  secured,  the  conclusion  was  reached  that  there  are 
three  generations.  The  writer  was  not  at  all  satisfied  with  this  con- 
clusion, and  in  1901  considerable  time  was  spent  in  studying  this  point. 

Examination  of  the  records  of  worms  caught  under  bands  showed 
that  at  certain  periods  greater  numbers  of  worms  went  under  bands 
than  during  the  intervals  between  these  times.  By  collecting  and 
studying  all  available  records  it  was  found  that  these  periods  were 
quite  constant,  and  this  appears  to  be  the  best  and  most  accurate  way 
of  determining  the  limits  and  number  of  generations. 

In  June,  1901,  circular  letters  were  sent  to  60  fruit  growers  in  dif- 
ferent parts  of  the  State  of  Idaho  asking  that  records  be  kept  of  the 
larvae  killed  under  bands.  But  very  few  growers  failed  to  answer. 
Among  those  who  responded,  a  few  stated  that  apples  were  not  grown 
in  their  sections;  others  banded  and  found  no  larvae  or  wormy  apples; 
and  still  others  could  send  no  record  on  account  of  crop  failure;  but 
a  large  number  sent  in  valuable  records.  These  records  were  tabulated 
and  curves  have  been  drawn  on  cross-section  paper. a 

"It  was  the  author's  intention  to  include  in  the  present  report  a  number  of  charts 
showing  these  curves;  but  owing  to  incompleteness  of  preparation,  and  other  circum- 
stances, these  charts  have  been  reserved  for  publication  in  a  later  report. 

L.  O.  H. 


16 


A  summary  of  the  more  important  records  is  here  given: 

Records  of  capture  of- codling-moth  larvse  under  bands. 


Year. 


1897 


1901 
1901 
1901 
1901 
1901 

1901 
1901 
1901 
1901 
1901 


Locality. 


Boise  

 do... 

Juliaetta 


Nam  pa  

Fayette  

 do  

 do  

Provo,  Utah. 

 do  

 do  

Hagerman  . , 

Lewiston  

Caldwell 


Observer  or 
source  of  rec- 
ord. 


Mr.  Avers  

 do  

Prof.  J,  M.  Aid- 
rich. 

H.  <;.  Gibson  .. 

.1.  Shearer  

 do  

 do  

Utah  Agricul- 
tural College 

 do  

 do  

K.  E.  Conner  .. 

s.  <;.  Iasman  . . 

Wm.  C.  George. 


Total  and  average. 


Num- 
ber of 

trees. 


140 
I  10 

-10 

4 
3 
80 
128 
23 

26 
34 
27 
4 
10 


ti.vj 


Pi  rst 

maxi- 
mum. 


July  17 
July  10 
July  20 

July  26 
July  L8 
July  l 
July  5 
....do ... 

July  13 
July  5 
.lulv  12 
....do... 
June  25 


Second 
maxi- 
mum. 


Sept.  1 
Sept.  L0 
Sept.  24 

Aug.  11 
Aug.  17 
Aug.  30 
...do ... 
Sept.  2 

Aug.  27 
Sept.  2 
Sept.  A 

Sept.  1(1 
Aug.  13 


I  )il  \  s 

be- 
tween 
nia  xi 

' 

Total 
ber  of 

worms. 

Time  be- 

Illicit  It" 

moval  of 

hands. 

Aver- 
age 
per 
tree. 

46 

12,247 

Weekly... 

87.48 

C>'2 

20,  JM 19 

 do  

1 49.  35 

66 

8,  620 

 do  

215. 50 

46 

467 

Daily  

116.  75 

(10 

215 

Weekly... 

71.66 

61 

3,  554 

do.... 

44. 42 

56 

1,690 

 do.... 

13.2 

59 

4,141 

do ... . 

180 

45 

2,829 

 do.... 

108.2 

50 

2, 880 

 do.... 

84.7 

54 

194 

 do.... 

8.2 

(10 

666 

6  per  mo.. 

166. 6 

49 

640 

2-5  days . . 

64 

55 

All  of  the  records  here  given  show  plainly  that  there  are  but  two 
maxima  of  larvae  entering"  bands.  There  are  many  sources  of  error 
in  obtaining  the  figures.  A  maximum  lasts  from  six  to  eight  days. 
Weekly  records  are  much  more  liable  to  error  on  account  of  the  length 
of  the  intervals.  The  average  length  of  time  between  maxima,  fifty- 
five  days,  is  undoubtedly  too  high,  as  the  records  of  Mr.  Gibson 
and  Mr.  George  show  the  time  to  be  forty-six  and  forty-nine  days, 
respectively. 

The  writer  has  secured  many  other  records,  but  they  can  not  be 
relied  upon  for  determining  the  number  of  generations,  as  some  of 
them  were  taken  on  too  few  trees,  and  others  commenced  too  late  or 
stopped  too  early  in  the  season. 

The  intervals  between  the  maxima  may  be  approximated  in  another 
way.  From  one  maximum  of  larvas  entering  bands  to  another  should 
be  the  length  of  the  life  cycle  of  the  insect.  The  length  of  the  stages 
in  the  life  of  this  insect  vary  greatly,  and  averages  can  be  accurately 
determined  only  b}^  a  great  number  of  experiments.  The  observa- 
tions of  the  writer  upon  the  length  of  the  different  stages  are  not 
so  complete  as  could  be  wished,  but  will  serve  to  show  the  averages 
approximately.  The  egg  stage  was  found  to  vary  from  three  to  eight 
days,  with  an  average  of  about  five  days.  The  life  of  the  larva  outside 
of  the  cocoon  is  from  fourteen  da}rs  to  twenty-five  days,  averaging 
about  twenty-one  days.  The  time  spent  in  the  cocoon  was  found  to  be 
from  twelve  to  twent}r-eight  da}^s,  averaging  about  twenty -two  days. 
The  egg-laying  period  was  observed  to  begin  the  second  day  after  the 
emergence  of  the  moth  and  continue  till  the  fourth  day.  Three  days 
would  probably  be  a  good  average.  The  total  of  these  averages  is 
fifty-one  days,  which  time  compares  favorably  with  the  interval 
between  the  maxima  of  larvse  entering  bands. 


Bui.  35,  New  Series,  Div.  of  Entomology,  U.  S.  Dept.  of  Agriculture. 


Plate  IV. 


Fig.  2.— Band  on  which  the  Remains  of  330  Cocoons  were 
counted. 


17 


By  adding  fifty-five  days  to  August  27  (the  average  time  in  1901  of 
the  maxima  for  the  second  generation),  we  should  expect  the  maximum 
of  the  third  generation  entering  bands.  At  that  date  (October  19)  no 
such  maximum  appears  upon  the  various  records.  It  was  noted  in 
1901  that  none  of  the  larvae  which  spun  cocoons  after  September  1 
transformed,  but  all  wintered  as  larvae.  In  1900  the  corresponding 
date  was  September  7. 

Mr.  McPherson  observed  the  period  of  the  greatest  number  of  eggs 
of  the  •first  generation  to  be  from  May  10  to  Ma}r  25.  The  writer 
observed  the  same  period  of  the  second  generation  to  be  from  about 
July  13  to  August  4.  But  when  the  time  came  for  the  egg  period  of 
the  third  generation  very  few  eggs  were  seen. 

Observations  were  made  daihT  in  the  orchards  and  the  courses  of 
these  generations  were  watched  as  carefully  as  possible.  On  account 
of  the  variability  of  location  of  orchards  and  the  overlapping  of  gener- 
ations, observation  is  very  liable  to  lead  to  error  and  can  not  be  taken 
as  proof  except  in  so  far  as  corroborated  by  other  evidence. 

It  has  been  often  noted  that  many  young  larvae  enter  the  apples  in 
September.  Whether  these  are  the  last  of  the  second  or  the  first  of 
the  third  generation  is  a  question  which  has  puzzled  the  writer.  But 
few  of  these  new  entrance  holes  were  observed  at  Boise  last  Septem- 
ber and  October,  and  the  writer  is  inclined  to  believe  that  the  larvae 
were  the  last  of  the  second  generation.  If  there  was  ever  a  full  third 
generation,  or  a  partial  one,  it  should  have  occurred  in  1901  by  reason 
of  the  earliness  of  the  season. 

Professor  Gillette's  article  on  the  generations  of  this  insect  has  been 
carefully  read.  In  general  the  writer's  conclusions  are  the  same,  but 
they  are  based  on  data  of  a  very  different  kind.  The  writer  can 
not  agree  with  Professor  Gillette  when  he  says  that  it  is  impossible 
for  a  partial  third  generation  to  be  produced.  A  study  of  the  life 
zones  will  show  that  we  should  expect  some  differences  between  the 
life  history  of  the  insect  in  Colorado  and  the  same  in  Idaho. 

The  writer  confesses  that  on  many  points  there  is  a  lack  of  data, 
and  on  this  account  does  not  wish  to  make  the  sweeping  assertion 
that  there  are  only  two  generations  of  the  codling  moth  in  southern 
Idaho.  Whether  or  not  there  may  be  a  partial  third  generation  is 
still  an  open  question  and  one  which  can  be  solved  only  by  careful  and 
accurate  work.  This  much,  however,  is  reasonably  certain:  The  third 
generation  is  of  little  or  no  importance,  whereas  in  the  past  it  has  been 
regarded  as  a  full  brood. 

All  future  work  will  be  based  upon  the  assumption  that  there  are 
two  generations.  It  is  hoped  that  next  season's  work  will  throw  more 
light  upon  these  doubtful  points  and  fully  establish  the  facts. 

'With  the  knowledge  that  there  is  no  fourth  brood  and  no  full  third 
27311— No.  35—02  2 


18 


brood,  the  question  of  the  control  becomes  easier  for  tin*  Idaho  fruit 
growers. 

OVERLAPPING  OF  GENERATIONS. 

The  overlapping  of  the  generations  is  one  of  the  conditions  which 
makes  the  control  of  the  insect  most  difficult.  In  1900,  from  July  7 
to  about  September  7.  the  writer  could  find  all  stages  of  the  insect. 
In  1901  about  the  same  conditions  were  noted. 

According  to  Mr.  Hitt's  experiments,  the  moths  in  the  spring  of 
L896  emerged  during  twenty-three  days. 

The  overlapping  renders  the  spraying  less  effective  than  it  would  be 
if  all  the  insects  were  in  the  same  stage  at  the  same  time. 

This  overlapping  is  accounted  for  by  the  fact  that  some  of  the 
insects,  being  in  favorable  situations,  grow  more  rapidly,  and  others, 
in  unfavorable  places,  lag  behind. 

CAUSES  AND  CONDITIONS  WHICH  AFFECT  THE  NUMBERS  OF 

THIS  INSECT. 

There  are  many  natural  conditions  which  tend  to  decrease  the  num- 
bers of  this  insect  in  the  Pacific  northwest.  Comparatively  few  of 
the  eggs  hatch.  Infertility,  excessive  dryness,  and  the  heat  of  the  sun 
seem  to  be  the  causes  of  this.  In  1901  thousands  of  the  young  larvae 
must  have  starved  on  account  of  not  having  apples  to  feed  upon. 

No  insect  parasites  were  noted  in  1901.  A  bird  belonging  to  the 
creepers  was  noted  at  Payette.  This  bird  was  very  active  in  hunting 
food  on  the  apple  trees,  and  without  doubt  destroyed  many  codling-moth 
larvae.  Growers  in  this  locality  say  that  the  bird  is  increasing  in 
numbers.  Many  pupae  were  found  to  be  dried  and  shrunken,  evidently 
killed  by  excessive  dryness.  In  more  humid  sections  bacterial  and 
fungus  diseases  kill  many.  But  if  these  unfavorable  conditions  and 
natural  enemies  alone  are  relied  upon,  almost  every  apple  in  an 
orchard  in  badly  infested  localities  will  be  wormy. 

There  are  many  reasons  which  may  be  assigned  for  the  large  num- 
ber and  the  great  destructiveness  of  the  codling  moth  in  Idaho.  The 
first  and  probably  the  most  important  fact  in  this  connection  is  that 
the  second  generation  is  more  numerous  than  the  first,  and  does  a 
larger  part  of  the  injury.  This  is  doubtless  due  to  the  climate.  It  is 
also  more  difficult  to  combat  this  second  generation  with  sprays  than 
it  is  the  first.  The  overlapping  of  the  generation  is  another  fact  that 
makes  the  spraying  more  difficult. 

One  reason  for  the  great  destructiveness  of  the  codling  moth  in  Idaho 
may  be  found  in  the  life  history  of  the  insect.  A  great  many  of  the 
fruit  growers  have  used  remedies  which  are  absurd.  When  the  proper 
remedies  were  used  the}'  were  not  used  in  the  proper  manner,  and 
hence  failure  resulted, 


19 


The  absence  of  remedial  measures,  use  of  improper  ones,  and 
improper  use  of  suitable  remedies  have  resulted  in  the  abundance  of 
the  insect,  and  have  caused  many  to  be  discouraged  and  to  have  the 
firm  belief  that  the  insect  can  not  be  controlled. 

The  presence  of  old,  neglected  orchards  is  a  source  of  constant  supply 
of  the  insect,  and  these  orchards  render  control  more  difficult. 

PREVENTIVE    MEASURES   EMPLOYED  AGAINST    THE  CODLING 

MOTH. 

There  has  been  in  the  past  an  idea  prevalent  among  the  fruit  growers 
of  the  Pacific  northwest  that  the  codling  moth  can  be  exterminated. 
That  idea  is  at  present  held  by  onl}r  a  few.  The  writer  has  always 
said  that  he  believed  it  practicable  to  entirely  eradicate  this  insect 
from  a  large  area.  In  an  isolated  orchard  there  are  strong  hopes  that 
it  can  be  done.  Next  season  an  attempt  will  be  made  to  exterminate 
the  insect  in  I.  B.  Perrine's  orchard  at  Blue  Lakes.  This  orchard  is 
practically  isolated  and  all  methods  will  be  used. 

The  very  best  general  result  that  can  be  expected  in  Idaho  is  to 
control  the  insect  so  that  its  ravages  will  not  exceed  10  per  cent. 

There  are  some  localities  in  Idaho  where  the  moth  has  not  yet 
appeared.  By  keeping  all  infested  fruit  and  old  apple  boxes  away 
from  these  localities,  immunity  may  be  secured.  In  other  localities 
at  high  altitudes  sudden  freezes  will  sometimes  reduce  the  numbers  of 
the  insect  to  such  an  extent  that  it  takes  two  or  three  years  for  it 
to  again  become  injurious.  Fruit  growers  in  these  localities  should 
use  the  utmost  vigilance,  and,  at  the  first  appearance  of  the  insect, 
remedies  should  be  applied  and  the  insect  exterminated  if  possible. 

When  the  wormy  fruit  is  picked  in  the  fall,  it  alwaj^s  contains  larvae 
in  different  stages.  This  fruit  is  stored  and  the  insects  complete  their 
growth  and  spin  their  cocoons  in  the  angles  of  the  boxes  and  in  cracks 
in  the  building.  In  the  spring,  immediately  after  emerging,  the  moths 
seek  the  nearest  orchard.  Where  apples  are  stored  in  great  quantity 
the  fruit  on  the  nearest  trees  is  all  damaged.  Two  well-marked  cases 
of  the  results  of  storing  apples  were  noted  in  Idaho  in  1900.  In  both 
cases  the  apples  growing  nearest  the  apple  house  (PI.  V)  were  all 
wormy.  In  one  case  the}T  were  evidently  infested  in  this  way  for 
about  5  rows  toward  the  center  and  about  15  rows  along  the  side  of 
the  orchard.  In  1901  this  place  was  still  the  place  of  worst  infesta- 
tion in  one  orchard.  These  conditions  may  easily  be  prevented  by 
shipping  the  apples  immediately  after  picking,  and  destroying  the 
culls.  If  the  fruit  must  be  stored,  the  windows  and  holes  of  the  store- 
house should  be  screened.  The  moths  will  collect  at  these  screens  and 
may  easily  be  crushed,  or,  if  the  house  is  so  tight  that  they  can  not 
escape,  they  may  be  left  to  die. 

Many  fruit  growers  have  committed  a  grave  error  in  regard  to  the 


20 


i 


crops  of  young  orchards.  The  first  crop  is  always  small,  and  many  do 
not  think  it  worth  while  to  use  means  against  the  moth  for  that  season. 
The  next  season's  crop  is  usually  larger  and  always  has  a  large  percent- 
age of  wormy  apples.  If,  however,  the  grower  had  destroyed  most  of 
the  worms  the  previous  season,  the  second  crop  would  have  suffered 
but  little  loss. 

It  has  often  been  observed  in  Idaho  that  the  apples  in  orchards  in 
which  the  trees  were  irrigated  by  flooding  were  less  worm}7  than  those 
in  orchards  which  are  irrigated  by  ditches.  Single  trees  or  blocks  of 
trees  in  ground  that  is  continually  moist  bear  less  wormy  fruit  than 
those  which  are  irrigated  only  occasionally.  The  on]y  explanation 
offered  for  these  facts  is  that  the  larva  will  not  spin  its  cocoon  in  a 
moist  place,  and  that  moisture  favors  the  diseases  of  the  insect. 

Whenever  possible,  the  writer  advises  that  the  ground  immediately 
around  the  trees  be  kept  moist,  especially  when  the  larvae  are  spinning 
their  cocoons  in  greatest  numbers.  Care  must  be  taken  in  doing  this, 
as  too  much  water  will  eventual ly  either  seriously  injure  or  kill  the 
trees. 

The  writer  has  noted  many  old,  neglected  orchards  in  various  locali- 
ties where  no  attempt  was  made  to  keep  the  insect  in  check.  It  needs 
no  explanation  that  these  orchards  furnish  a  constant  supply  of  moths 
to  adjoining  orchards,  and  in  that  way  the  loss  in  the  orchard  which  is 
well  cared  for  is  greater  than  it  would  be  if  both  received  good  care. 

In  towns  and  cities  many  people  have  in  their  lawns  apple  trees  which 
also  furnish  a  constant  supply  of  the  insects.  These  people  wish  the 
trees  for  shade  only  and  have  no  desire  to  raise  fruit.  The  writer  has 
approached  these  people  many  times  when  the  opportunity  presented 
itself,  and  showed  them  what  they  could  do  to  lessen  the  difficulty. 
The  people  who  desire  apple  trees  for  shade  only  could  easily  destroy 
all  the  apples  early  in  the  season,  and  thus  no  damage  would  be  done. 

REMEDIAL  MEASURES  EMPLOYED  AGAINST  THE  CODLING  MOTH. 

To  intelligently  apply  remedial  measures  necessitates  as  a  first  essen- 
tial an  accurate  knowledge  of  the  life  history  of  the  insect.  With  this 
as  a  basis,  any  fruit  grower  may  adapt  the  measures  emplo3Ted  to  his 
circumstances.  It  will  readily  be  seen  that  there  are  certain  periods 
in  the  life  of  this  insect  when  it  is  vulnerable,  and  others  when  it  is 
comparatively  safe. 

The  few  experiments  which  have  been  made  against  the  insect  show 
that  it  is  impracticable  to  undertake  the  destruction  of  the  eggs. 

MEASURES  AGAINST  THE  LARViE. 


A  large  majority  of  all  the  remedial  measures  that  have  been  used 
are  against  the  insect  in  this  stage. 


Bui.  35,  New  Series,  Div  of  Entomology,  U.  S  Dept.  of  Agriculture. 


Plate  V. 


Views  in  Orchard  of  Hon.  Edgar  Wilson,  showing  Location  of  Apple  House 
in  Relation  to  Orchard. 


21 


Spraying. 

Against  the  young  larvae  entering  the  fruit,  spraying  with  arsenical 
poisons  is  most  generally  used.  The  object  is  to  place  the  poison  in 
such  places  that  when  the  }Toung  larva?  enter  the  apple  the}7  will  get 
some  of  the  poison  with  the  first  few  meals. 

EARLY  SPRAYINGS. 

The  best  time  to  spray  is  immediately  after  the  blossoms  fall  and 
before  the  lobes  of  the  calyx  are  closed.  By  spraying  at  this  time  the 
open  calyx  forms  an  excellent  place  to  catch  the  poison,  and  by  the 
closing  of  the  lobes  it  is  retained  for  some  time.  As  before  stated, 
from  80  to  S5  per  cent  of  the  larvae  of  the  first  generation  enter  by 
the  calyx.  Many  cases  might  be  cited  showing  the  efficiency  of  this 
first  spraying.  One  example  will  suffice:  In  the  spring  of  1901  the 
writer  examined  two  orchards,  separated  only  by  a  road.  One  had 
been  spra}Ted  thoroughly  and  other  measures  had  been  used;  the  other 
had  not  been  spra}Ted,  and  no  other  measures  had  been  used.  From 
the  first  generation  about  10  per  cent  of  the  apples  in  the  spra}Ted 
orchard  were  wormy;  in  the  unsprayed  orchard  25  to  30  per  cent  were 
wormy.  By  count  it  was  determined  that  in  the  unsprayed  orchard 
83  per  cent  of  the  wormy  apples  had  been  entered  through  the  calyx, 
while  in  the  sprayed  orchard  only  about  10  per  cent  of  the  larvae 
which  entered  by  the  calyx  had  escaped  the  poison. 

On  account  of  not  being  able  to  commence  this  work  in  the  early 
spring,  the  writer  was  unable  to  make  observations  upon  the  hatching 
of  the  eggs  of  the  first  generation.  Mr.  Hitt  furnishes  the  following 
data:  In  1896  the  first  moths  appeared  May  5,  and  the}T  continued  to 
emerge  until  May  25.  He  also  noted  that  the  apple  trees  were  in  full 
bloom  May  1.  In  1901  the  moths  developed  in  advance  of  the  bloom- 
ing period. 

Mr.  McPherson  noted  the  appearance  of  the  first  moths  April  23,  in 
1901,  and  the  first  eggs  May  10,  which  was  about  the  time  that  the 
blossoms  fell  from  the  Winesap,  Jonathan,  Golden,  and  Ben  Davis 
varieties. 

Investigators  in  different  parts  of  the  country  have  found  that  the 
poison  stays  in  the  calyx  and  is  effective  for  at  least  a  week;  hence, 
the  lateness  of  the  moth  offers  no  difficulty.  Exactly  what  the  moths 
do  between  the  time  of  emerging  and  egg  laying  still  remains  to  be 
studied  in  this  locality.  Professor  Cordley  has  noted  the  same  state 
of  affairs  in  Oregon,  and  thinks  that  the  cool  nights  prevent  the  moths 
from  ovipositing. 

The  second  spraying  should  be  done  about  a  week  or  ten  days  after 
the  first.  This  spraying  is  intended  for  late  larvae  of  the  first  genera- 
tion. 


22 


Tn  cases  of  very  bad  infestation,  or  if  extermination  is  aimed  at, 
the  writer  would  recommend  a  third  spraying'  in  this  connection. 

The  writer  has  neglected  no  opportunity  to  impress  upon  the  fruit 
growers  of  the  Pacific  Northwest  that  the  first  spraying  is  by  far  the 
most  important  remedial  measure  against  this  insect,  and  has  gone  so 
far  as  to  state  as  his  belief  that  one  good  spraying  when  the  calyx 
is  open  saves  more  apples  than  all  of  the  other  remedial  measures 
together. 

LATER  SPRAYINGS. 

The  question  of  late  sprayings  is  one  of  the  points  now  under  dis- 
cussion among  entomologists  and  horticulturists.  The  facts  gleaned 
from  publications,  letters,  and  conversations  with  those  in  the  best 
position  to  know  are  as  follows: 

Professor  Gillette,  of  Colorado,  writes  that  in  Colorado  there  are 
some  fruit  growers  who  advocate  9  or  10  sprayings,  while  others 
say-  that  they  obtain  just  as  good  results  with  2  or  3.  Professor  Gil- 
lette says  he  has  two  cases  in  mind  where  as  good  results  as  one  could 
wish  were  obtained  with  only  2  sprayings.  He  says  he  can  hardly  see 
how  more  than  a  slight  benefit  can  be  obtained  by  any  spraying  after 
the  second. 

Professor  Card,  in  his  Nebraska  bulletin,  rather  discourages  later 
sprayings. 

Prof.  M.  V.  Slingerland,  in  his  bulletin  upon  this  subject,  states 
that  he  can  not  see  how  the  larva?  get  any-  of  the  poison  from  the  side 
of  the  fruit. 

Professor  Washburn,  of  the  Oregon  station,  concludes  that  2  or  3 
sprayings  will  save  from  70  to  80  per  cent  of  the  early  apples,  and 
that  6  sprayings  will  save  from  65  to  70  per  cent  of  the  winter  apples. 

Professor  Cordley  says  that  now  he  can  obtain  a  much  higher  effi- 
ciency. 

The  writer  visited  the  orchard  of  Olwell  Bros.,  Centralpoint,  Oreg., 
and  estimated  their  loss  in  1901  to  be  5  per  cent  from  the  codling 
moth,  and  Mr.  James  Olwell  told  him  that  the  loss  was  greater  than 
in  1900.  Many  other  apple  growers  in  southern  Oregon  are  obtaining 
similar  results  every  year. 

Mr.  Gus  Goeldner,  of  Boise,  Idaho,  writes  that  by  spraying  he  saved 
98  per  cent  of  his  apples,  and  Mr.  C.  Plinze,  of  Payette,  Idaho,  reported 
to  the  writer  in  1900  that  by  spraying  he  had  saved  95  per  cent  of  his 
apples.  Many  statements  like  these  from  Mr.  Goeldner  and  Mr. 
Hinze  will  not  stand  investigation.  In  fact,  many  people  are  deceiv- 
ing themselves,  and  get  no  such  results  with  spraying  alone.  The 
writer  does  not  believe  it  possible  to  save  even  85  or  90  per  cent  in 
southern  Idaho  by  spraying  alone. 

This  question  of  later  spraying  has  become  one  of  the  most  impor- 


23 


tant  features  of  the  control  of  this  insect.  The  writer  has  made  many 
observations  as  to  the  efficiency  of  the  spray.  It  is  a  common  thing 
in  sprayed  orchards  to  find  places  on  the  apples  where  larva?  had 
entered  and,  a  day  or  two  after  entering,  had  died.  This  condition 
was  found  to  be  much  more  frequent  in  sprayed  orchards  than  in  those 
which  were  unsprayed.  Without  doubt  these  larvae  were  killed  b}r 
the  spraying.  Exactly  how  and  when  the  larvae  get  the  poison  is  a 
question.  As  has  been  stated  before,  the  larva?  eat  but  little  of  the 
skin  or  flesh  of  the  apple  while  entering.  The  cavities  in  which  they 
are  found  dead  are  usually  of  such  size  that  it  would  take  the  larva?  a 
day  or  two  to  make  them.  Particles  of  lime  are  sometimes  found  in 
these  cavities.  While  seeking  a  place  of  entrance  the  larva  may  get 
some  of  the  poison,  and  it  may  live  a  day  or  so  after  getting  the  fatal 
dose.    Some  of  the  spray  may  get  into  the  entrance  hole  and  be  eaten. 

Soon  after  dying,  the  larvae  become  dry  and  shrunken  and  can  be 
distinguished  only  by  the  presence  of  the  head. 

The  writer  once  noted  a  case  where  TO  cent  of  the  larva?  entering 
in  the  course  of  two  or  three  days  were  found  dead.  It  is  extremely 
probable  that  a  considerable  part  of  them  died  naturally.  Many 
other  observations  were  made,  but  never  was  such  efficiency  noted 
again. 

In  many  orchards  that  had  been  well  sprayed,  hundreds  of  these 
spots  were  noted  which  had  been  caused  by  the  larva?  and  upon  exam- 
ination no  larvae  were  found. 

In  1901  the  writer  found  a  larva  which  had  begun  an  entrance  hole 
and  had  just  died. 

On  account  of  these  observations  and  the  general  results  obtained 
by  spraying  and  banding,  the  writer  has  no  hesitancy  in  recommend- 
ing these  later  sprayings.  Without  doubt  the  efficiency  is  much  less 
than  in  case  of  the  tirst  spraying,  but  the  writer  believes  them  well 
worth  the  expense. 

The  writer  has  found  that  many  growers  spray  when  they  have 
time  and  do  not  take  into  consideration  the  stage  the  insects  are  in. 
Some  spray  every  three  weeks  and  others  spray  when  they  see  the 
number  of  entrance  holes  increasing.  As  already  shown,  the  larva? 
are  entering  more  or  less  all  summer;  but  at  two  certain  periods  of 
the  season  there  are  many  more  entering  than  at  other  times.  One 
can  easily  see  that  the  theoretically  perfect  time  for  spraying  would 
be  when  the  larva1  are  entering  the  fruit  in  greatest  numbers.  It  is 
therefore  essential  to  recommend  simple,  practical  methods  for  deter- 
mining this  period  of  greatest  entrance.  The  writer  advises  every 
one  who  wishes  to  spray  for  the  codling  moth  to  keep  a  daily  band 
record  on  about  ±  trees.  By  a  study  of  this  record  the  maximum  can 
be  easily  found.  In  the  summer  this  maximum  will  be  found  some- 
times between  June  25  and  July  15.    By  experiment  we  have  found 


that  the  maximum  of  egg  hutching  should  occur  twenty-nine  days 
after  the  time  w  hen  the  greatest  number  of  the  preceding  generation 
entered  the  hands.  In  the  record  made  by  Mr.  Gibson  it  will  be 
noted  that  the  first  maximum  occurred  June  26,  and  that  by  adding 
twenty-nine  days  we  get  the  date  of  July  26.  As  the  maximum  of 
egg  hatching  extends  over  some  time,  spraying  must  be  done  before 
this  date  in  order  to  get  those  which  are  early.  In  this  instance  the 
spraying  should  have  been  done  between  July  15  and  August  -1. 
Observation  in  the  orchard  in  which  the  record  was  taken  showed 
the  period  of  greatest  number  of  eggs  to  be  between  July  L3  and 
August  4. 

The  writer  has  never  had  an  opportunity  to  test  this  recommenda- 
tion thoroughly.  Many  practical  tests  were  made,  and  the  results  of 
these  show  that  it  is  absolutely  essential  for  highest  efficiency  to  do 
the  spraying  when  the  largest  number  of  larvae  are  entering.  The 
writer  would  advise  two  thorough  sprayings  during  this  period. 
Another  ma}T  be  made  if  infestation  is  bad. 

MATERIAL  FOR  THE  SPRAY. 

It  is  recommended  in  every  case  that  arsenical  sprays  be  used  for 
this  work.  Paris  green  is  most  used  in  the  proportions  of  1  pound  to 
160  gallons  of  water  with  2  pounds  of  lime.  By  the  use  of  this  solu- 
tion excellent  results  are  secured,  but  on  account  of  its  cost  and  liability 
to  settle  man}T  are  abandoning  it  for  the  white  arsenic  compounds. 

London  purple  is  rarely  used  alone.  Mr.  Tiner,  of  Boise,  and  Olwell 
Brothers,  of  Centralpoint,  Oreg.,  are  using  a  combination  of  Paris 
green  and  London  purple.  Olwell  Brothers  use  the  following  propor- 
tion: Water,  120  gallons;  Paris  green  and  London  purple,  9  ounces 
each;  and  lime,  2  pounds.  Mr.  Tiner  believes  that  in  this  way  the 
poisons  arc  kept  in  suspension  better.  Such  good  results  are  obtained 
that  these  growers  are  loth  to  adopt  other  compounds.  White  arsenic 
compounds  are  being  used  more  and  more  with  results  just  as  good  as 
those  obtained  with  other  arsenicals.  Dr.  H.  P.  Ustick,  of  Boise,  and 
Mr.  C.  Hinze,  of  Payette,  have  used  them  successfully.  Information 
as  to  the  methods  of  making  these  spra}Ts  have  been  published  in  Idaho 
and  the  fruit  growers  are  familiar  with  them. 

As  far  as  the  writer  can  learn,  lead  arsenate  has  never  been  used  as  a 
spray  against  this  insect  in  the  Pacific  northwest.  The  writer  believes 
that  it  will  be  found  excellent,  and  will  use  it  in  experiments  next 
season.  There  are  a  few  fruit  growers  who  use  whale-oil .  soap  with 
the  sodium  arsenite.  Man}r  observations  were  made  in  connection 
with  the  use  of  this  mixture  to  ascertain  if  it  caused  the  poison  to 
remain  on  the  fruit  longer.  Without  doubt  this  is  the  case,  but  the 
soapy  solution  collects  on  the  under  sides  of  the  apples  and  damages 


25 


them  materially.  In  one  block  of  Jonathans  fully  50  per  cent  of  the 
clean  apples  had  spots  caused  by  the  soap. 

It  is  intended  that  future  work  will  show  exactly  which  one  of  these 
arsenites  is  the  most  effective. 

EXPENSE  OF  SPRAYING. 

From  the  data  given  by  the  fruit  growers  it  is  found  that  spraying- 
is  comparatively  inexpensive.  The  material  to  spray  2,000  trees  costs 
about  85.  Orchardists  always  have  teams  and  men  already  employed, 
so  that  the  extra  expense  on  account  of  spraying  is  very  small  com- 
pared with  the  benefit.  By  the  use  of  a  gasoline-power  outfit  the  work 
can  be  done  much  more  quickly,  and.  in  a  large  orchard,  with  less 
expense  in  the  end.  When  quickly  done  the  cost  should  be  less  than 
1  cent  per  tree  per  spraying.  If  inferior  appliances  are  used,  or  the 
trees  are  larger  than  the  average,  the  cost  will  be  greater.  Labor  is 
the  most  expensive  factor  in  spraying. 

Picking  and  Destroying  Wormy  Fruit. 

While  the  larva1  are  feeding  in  the  apples,  these  may  be  picked  and 
destroyed.  This  is  especially  recommended  as  an  effective  remedy  for 
use  early  in  the  season.  As  has  often  been  shown,  thinning  the  apples 
to  -t  inches  apart  produces  a  finer  quality  of  fruit  and  causes  the  tree 
to  bear  well  each  year.  It  is  strongly  recommended  that  in  Idaho, 
between  June  1  and  1.3.  the  fruit  be  thinned,  and  that  in  thinning  all 
wormy  apples  be  removed  and  destroyed.  The  writer  believes  it  well 
worth  while  to  thin  apples  in  order  to  kill  the  codling-moth  larvae, 
without  considering  the  other  advantages.  Picking  and  destroying  the 
wormy  apples  during  July  and  August  is  too  expensive  to  be  of  any 
great  value  in  a  large  commercial  orchard. 

In  order  to  get  best  results,  orchards  should  be  cleared  of  all  wind- 
falls as  promptly  as  possible,  so  that  the  worms  contained  may  be 
destroyed.  In  some  small  orchards  it  is  the  practice  to  allow  hog-  to 
run  in  the  orchard  and  pick  up  the  windfalls.  It  would  be  an  almost 
endless  and  expensive  undertaking  to  pick  up  and  destroy  the  wind- 
falls in  a  large  orchard  every  day  or  two.  The  writer  does  not  think 
it  worth  the  expense  if  the  proper  precautions  are  taken  in  the  use  of 
the  bands. 

The  cheapest  and  most  effective  way  to  get  rid  of  culls,  windfalls, 
and  the  apples  picked  in  thinning  is  to  bury  them.  Water  should  be 
allowed  to  run  into  the  holes,  and  not  less  than  10  inches  or  a  foot  of 
earth  should  cover  the  fruit.  If  the  earth  is  in  clods,  it  will  be  well 
to  pack  it.  Many  observations  were  made  during  the  season  of  1901 
to  ascertain  the  effect  of  burying  in  this  way.  In  many  cases  the  larvae 
succumbed  to  diseases  induced  by  the  moisture.    Most  of  them  spun 


26 


cocoons  at  the  surface  of  tin1  apples,  hut  the  moths  were  unable  to 
escape.  Larva'  put  in  the  earth  remain  a  longer  time  in  the  cocoon 
than  they  otherw  ise  would. 

Banding. 

When  the  larvae  leave  the  apples  and  seek  a  place  in  which  to  spin 
their  cocoons  another  point  of  attack  may  be  taken  advantage  of  by 
furnishing  a  suitable  place  for  the  spinning  of  the  cocoons  and  by  kill- 
ing the  worms  after  they  have  entered  the  place.  This  object  is  accom- 
plished by  placing  cloth  bands  from  8  to  1<>  inches  wide  around  the 
trunks  of  the  trees.  If  the  trees  are  large,  each  of  the  larger  branches 
may  also  be  banded.  The  bands  may  be  made  of  an}'  heavy  fabric, 
such  as  burlap,  old  clothes,  old  carpet,  etc.  The  band  should  be  folded 
once  lengthwise  and  placed  around  the  trees  about  li  to  '2  feet  from 
the  ground.  After  placing  the  band  around  the  tree,  a  small  nail 
should  be  driven  through  the  ends  firmly  into  the  tree.  The  head  of 
the  nail  should  be  nipped  off.  Subsequent  removal  and  replacing  of  the 
bands  may  be  done  more  quickly  by  this  method  of  fastening. 

The  number  of  worms  caught  under  these  bands  is  sometimes  aston- 
ishing. (PI.  IV.  fig.  2.)  It  is  quite  common  to  find,  during  a  maximum 
period,  from  50  to  100  each  week  for  two  or  three  weeks  under  the 
band  on  a  single  large  tree.  The  highest  number  Professor  Aldrich 
records  as  caught  on  one  tree  from  July  7  to  October  15  is  1:9-1.  Under 
neglected  bands  as  many  as  200  have  been  found  at  one  time.  It  is 
found  in  orchards  that  have  been  sprayed  and  banded  that,  in  Septem- 
ber or  the  first  part  of  October,  the  worms  are  very  scarce,  thus  in  a 
way  showing  the  efficiency  of  the  methods. 

Apparently  banding  is  one  of  the  most  effective  methods,  and  there 
are  two  highly  essential  features  that  can  not  be  emphasized  too 
strongly:  (1)  All  places  suitable  for  spinning  cocoons  other  than  bands 
must  be  removed  or  rendered  unsuitable.  The  loose  bark  should  be 
scraped  from  the  tree,  all  holes  and  cracks  in  the  trees  should  be  filled 
with  mud  or  cement,  and  the  earth  around  the  trees  should  be  kept- 
moist  during  the  periods  when  the  worms  are  most  numerous.  (2)  At 
regular  intervals  the  bands  must  be  examined  and  all  the  larvae  and 
pupa*  killed.  The  interval  between  examinations  of  the  bands  recom- 
mended heretofore  has  been  six  or  seven  days.  During  the  summer 
of  1901  the  writer,  by  numerous  experiments  and  observations,  found 
that  every  ten  or  eleven  days  is  often  enough  to  kill  the  worms.  This 
extension  of  time  between  the  changing  of  the  bands  reduces  the  cost 
of  banding  considerably,  as  instead  of  II  or  15  changes  of  hands  there 
is  need  of  only  10  or  11. 

Many  methods  have  been  devised  for  killing  the  larva1,  but  the  most 
rapid  and  effective  is  either  to  crush  them  or  cut  them  in  two  with  a 
knife. 


27 


At  the  suggestion  of  Hon.  Edgar  Wilson  the  writer  again  experi- 
mented with  Paris  green  in  and  under  the  bands  to  find  whether  or  not 
the  worms  would  get  any  of  the  poison  and  be  killed.  Five  bands 
were  thoroughly  soaked  in  a  strong  solution  of  Paris  green  and  a 
large  quantity  of  the  dry  poison  was  dusted  on  10  others.  These 
were  placed  upon  trees  and  examined  every  day  or  two.  .Not  a  single 
larva  was  found  dead.  Mamr  were  found  to  have  spun  their  cocoons 
in  the  poison  which  was  laying  in  the  crotches  of  the  trees. 

Bands  should  be  placed  upon  the  trees  not  later  than  the  middle  of 
June  and  should  not  be  finally  removed  until  about  a  week  after  the 
crop  has  been  harvested.  By  a  close  watch  on  a  few  bands  one  can 
tell  when  the  worms  begin  to  descend  in  the  spring.  After  the  first 
week  in  September  it  is  found  that  very  few,  if  any,  larvae  change  to 
pupae  and  emerge.  It  is  not  advisable  to  let  any  bands  stay  on  the 
trees  all  winter,  as  they-  rot,  and  the  cost  of  bands  is  a  considerable 
item  in  a  large  orchard. 

Many  fruit  growers  believe  that  under  favorable  circumstances  they 
can  save  almost  half  their  crop  by  banding  alone. 

It  is  strongly  urged  that,  late  in  the  fall,  during  the  winter,  or  early 
in  the  spring,  the  orchard  be  examined,  and  all  the  larva?  found  in 
crevices  and  under  the  bark  of  the  trees  killed. 

MEASURES  AGAINST  THE  ADULT. 

TRAP  LANTERNS. 

Considerable  effort  has  been  made  to  put  the  facts  about  trap  lan- 
terns before  the  Idaho  apple  growers.  The  agent  for  a  patented  trap 
sold  240  in  Boise  and  vicinity.  He  claimed  that  he  caught  6  codling 
moths  in  one  night.  A  majority  of  the  growers  who  bought  these 
traps  found  out  for  themselves  that  this  method  is  useless.  A  very 
few  still  advocate  its  use.  The  writer  did  not  think  the  method  worthy- 
of  experiment. 

BAITING  THE  MOTH. 

One  fruit  grower  at  Mountainhome  uses  buckets  of  cider  or  vinegar, 
with  which  he  says  he  catches  large  numbers  of  codling  moths.  Dr. 
Riley's  experiences  show  that  these  catchings  must  have  been  acci- 
dental. The  writer  set  out  some  of  these  cider  buckets  and  in  two 
weeks  while  the  moths  were  flying  caught  but  few.  The  notes  on  the 
experiment  were  misplaced,  but  the  writer  remembers  that  about  10 
codling  moths  were  caught  and  many  Noctuids.  At  best  the  results 
of  the  method  would  in  no  way  be  commensurate  with  the  expense. 

r£sum£  and  conclusion. 

As  has  been  before  stated,  the  codling  moth  can  not  be  exterminated 
throughout  the  Pacific  northwest.     Reduction  of  the  damage  with 


28 


least  expense  has  been  the  object  in  view.  The  writer  believes  that 
by  the  intelligent  use  of  the  methods  herein  given  the  moth  can  be  so 
well  controlled  that  the  injuries  will  be  between  2  and  10  per  cent. 
With  the  insect  under  control,  it  will  not  be  necessary  to  use  all  of 
these  measures  every  year. 

The  writer  has  never  had  the  opportunity  of  putting  all  of  these 
recommendations  into  practice  in  one  orchard.  This  would  have  been 
done  had  it  not  been  for  the  freeze  of  1901.  Advice  was  given  many 
times  as  to  the  treatment  of  orchards  and  the  results  were  noted  as  far 
as  possible.    Some  of  the  successes  are  here  given: 

M.  A.  Kurtz,  Nampa,  Idaho,  has  an  orchard  of  about  2,500  trees, 
many  of  which  are  stunted  partly  on  account  of  lack  of  care.  In  1898 
there  was  less  than  a  full  crop,  about  50  per  cent  being  damaged;  in 
1899  there  was  a  full  crop,  but  only  100  boxes  of  clean  apples  were 
harvested.  In  1900  there  was  about  one-fourth  of  a  crop,  and  all  were 
wormy.  In  1901  Mr.  Gibson,  in  charge,  began  good  cultivation,  spray- 
ing, and  banding.  There  was  probably  over  a  half  crop.  The  trees 
were  all  sprayed  with  Paris  green  four  times,  and  a  majorit}T  of  them 
a  fifth  time.  Bands  were  well  attended  to.  The  writer  visited  the 
orchard  frequently  during  the  season,  the  last  visit  being  made  the 
latter  part  of  September,  when  the  fruit  was  estimated  to  be  damaged 
as  follows:  Ben  Davis,  5  per  cent;  Steele's  Winter  Red,  10  per  cent, 
and  Blue  Pearmain,  25  per  cent.  A  few  Ben  Davis  trees  showed  10 
per  cent  of  damage.  A  large  amount  of  the  fruit  was  undersized. 
The  writer  could  not  get  figures  after  the  crop  was  harvested,  but  he 
believes  the  work  done  against  the  codling  moth  was  quite  successful. 
The  only  cause  of  uncertainty  was  the  fact  that  the  crop  was  small 
the  year  before,  and  the  insect  might  possibly  have  been  reduced 
on  this  account. 

Hon.  Edgar  Wilson  has  an  orchard  (PI.  V)  near  Boise,  containing 
about  4,000  trees,  about  2,000  of  which  were  bearing.  There  was  a 
light  crop  of  Jonathans  and  about  one-half  crop  of  Ben  Davis.  Only 
the  early  spra}rings  were  made,  and  they  were  well  done.  Bands 
were  well  attended  to.  The  later  sprayings  were  not  made,  and  the 
bulk  of  the  injury  was  done  by  the  second  generation.  Not  over  40 
per  cent  of  the  apples  in  this  orchard  were  free  from  worms.  In  1900 
from  85  to  90  per  cent  were  saved. 

Mr.  Tiner,  of  Boise,  has  about  400  trees,  in  a  badly  infested  locality. 
Spray  ing  and  banding  were  well  done,  but  only  about  30  per  cent  of 
the  fruit  was  saved.    In  1900,  80  per  cent  was  the  amount  saved. 

The  losses  in  many  other  well-treated  orchards  with  small  crops 
varied  from  20  to  80  per  cent.  In  those  orchards  where  the  loss  was 
higher  only  partial  measures  were  used..  In  untreated  orchards  in 
badly  infested  localities  the  loss  was  always  about  100  per  cent.  The 


29 


reason  of  these  excessive  losses,  even  when  the  best  measures  were 
used,  may  be  accounted  for  by  the  fact  that  the  freeze  killed  a  large 
percentage  of  the  fruit,  while  the  moths  survived. 

Olwell  Brothers,  of  Oregon,  spray  every  three  weeks  during  the  sea- 
son, and  the  writer  examined  the  orchard  in  October  and  estimated 
only  5  per  cent  loss  from  the  codling  moth. 

The  writer  feels  grateful  to  the  Idaho  growers  for  the  way  they 
have  adopted  his  recommendations.  Plans  have  been  partially  made 
for  next  season's  work.  In  general,  the  plans  are  to  select  one  or  two 
typical  badly  infested  orchards  and  there  apply  remedial  and  pre- 
ventive measures  to  demonstrate  exactly  what  can  be  done  against  the 
insect.  The  writer  has  no  fears  that  the  results  will  not  substantiate 
all  that  is  claimed  for  the  remedial  measures. 


O 


